The MMACHC gene encodes a protein known as Methylmalonic aciduria and homocystinuria type C (protein). Mutations in the MMACHC gene are associated with an inborn error in metabolism known as methylmalonic acidemia, which may also be known as methylmalonic aciduria and homocystinuria, cblC type. (The cblA, cblB, cblD and cblF types are caused by mutations in other genes; specifically, the MMAA, MMAB, MMADHC and LMBRD1 genes, respectively.) Wikipedia

This condition is typically inherited as an autosomal recessive condition.

MMACHC SNPs in SNPedia include:

rs398124292, aka 271A, which in one study accounted for 40% of all mutant alleles